So I put a hsr42 on my 1993 evo. The air filter backing plate holes doesn’t match to the mikuni adapter. I want to also upgrade the air filter system. Any suggestions that will fit?

 

Sounds like you have the wrong adapter. You need the universal one that has like 6 on it. Im running a arlen ness back plate and filter on my 1993 FLHS and it fit just fine. My motor is a head breather. Yours should be the same.